Methods and apparatus for fabricating gas turbine engine combustors

ABSTRACT

A method for fabricating a dome assembly for a gas turbine engine combustor includes forming an annular dome plate including a plurality of substantially circular eyelets circumferentially spaced thereon, coupling a seal plate to the dome plate at each eyelet such that an opening defined in each seal plate is aligned substantially concentrically with respect to a respective eyelet, coupling a baffle to each seal plate such that an opening defined in each baffle is aligned substantially concentrically with respect to a respective eyelet, and coupling a swirler assembly having an integrally formed swirler and flare cone to each seal plate such that the flare cone extends at least partially through the baffle opening, and such that cooling air may be directed towards the flare cone through openings formed in the assembly.

BACKGROUND OF THE INVENTION

This application relates generally to gas turbine engines and, moreparticularly, to combustors for gas turbine engine.

At least some known gas turbine engines include a compressor thatprovides compressed air to a combustor wherein the air is mixed withfuel and ignited for generating hot combustion gases. The gases flowdownstream to one or more turbines that extract energy therefrom topower the compressor and provide useful work such as to power anaircraft in flight.

At least some known combustors used in gas turbine engines typicallyinclude inner and outer combustion liners joined at their upstream endsby a dome assembly. The dome assembly includes an annular spectacleplate or dome plate and a plurality of circumferentially spaced swirlerassemblies or cups. Fuel is supplied to the dome where it is mixed withair discharged from the swirler assemblies to create a fuel/air mixturethat is channeled to the combustor. Known combustors include a bafflethat is exposed to high temperatures generated during the combustionprocess, and cooling air passages that channel cooling air to thebaffle. Known cooling air channels do not regulate a precise air flow tothe baffle, but rather, the cooling air is forced through gaps definedbetween the edges of the dome plate and the baffle.

In at least one known combustor, the dome assembly is manufactured by abrazing process, wherein the swirler assemblies and baffles are brazedto the dome plate. The brazing process may be a time consuming andlabor-intensive procedure that may require the use of multiple fixturesand many expensive materials. Typically, at least some of the brazejoints may be difficult to inspect, and may require considerable rework.Moreover, in at least one known combustor dome assembly, repairs aredifficult or impossible, in that the repair of a brazed componentrequires that the dome assembly go through a braze oven which mayundesireably cause damage to joints that previously did not requirerepair.

BRIEF SUMMARY OF THE INVENTION

In one aspect, a method for fabricating a dome assembly for a gasturbine engine combustor is provided. The method includes forming anannular dome plate including a plurality of substantially circulareyelets circumferentially spaced thereon, coupling a seal plate to thedome plate at each eyelet such that an opening defined in each sealplate is aligned substantially concentrically with respect to arespective eyelet, coupling a baffle to each seal plate such that anopening defined in each baffle is aligned substantially concentricallywith respect to a respective eyelet, and coupling a swirler assemblyhaving an integrally formed swirler and flare cone to each seal platesuch that the flare cone extends at least partially through the baffleopening, and such that cooling air may be directed towards the flarecone through openings formed in the assembly.

In another aspect, a dome assembly for a gas turbine engine combustor isprovided that includes at least one swirler assembly that includes aprimary swirler and a secondary swirler. The secondary swirler is formedintegrally with a flare cone, and the secondary swirler includes acooling circuit formed therein channeling cooling air towards the flarecone.

In a further aspect, a gas turbine engine is provided. The gas turbineengine includes a combustor that includes at least one dome assembly.The at least one dome assembly includes at least one swirler assemblyincluding a primary swirler and a secondary swirler. The secondaryswirler is formed integrally with a flare cone. The secondary swirlerincludes a cooling circuit defined therein for channeling cooling airtowards the flare cone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a gas turbine engine;

FIG. 2 is a schematic cross-sectional view of a combustor that may beused with the gas turbine engine shown in FIG. 1;

FIG. 3 is a perspective view of a dome plate; and

FIG. 4 is an enlarged cross-sectional view of the dome assembly shown inFIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic illustration of a gas turbine engine 10 includinga low pressure compressor 12, a high pressure compressor 14, and acombustor 16. Engine 10 also includes a high pressure turbine 18, and alow pressure turbine 20 arranged in a serial, axial flow relationship.Compressor 12 and turbine 20 are coupled by a first shaft 24, andcompressor 14 and turbine 18 are coupled by a second shaft 26. In oneembodiment, gas turbine engine 10 is a CF34-3 engine commerciallyavailable from General Electric Company, Cincinnati, Ohio.

In operation, air flows through low pressure compressor 12 from anupstream side 28 of engine 10. Compressed air is supplied from lowpressure compressor 12 to high pressure compressor 14. Highly compressedair is then delivered to combustor assembly 16 where it is mixed withfuel and ignited. Combustion gases are channeled from combustor 16 todrive turbines 18 and 20.

FIG. 2 is a cross-sectional view of a combustor, such as combustor 16,that may be used with gas turbine engine 10. Combustor 16 includes aninner liner 30 and an outer liner 32. Inner and outer liners 30 and 32are joined at an upstream end 36 by a dome assembly 40. The crosssection shown in FIG. 2 is taken through one of a plurality of swirlerassemblies 42 that are mounted on dome assembly 40. A fuel line 44delivers fuel to a fuel injector (not shown) that supplies fuel to aninlet 46 of swirler assembly 42. Fuel is mixed with air in swirlerassembly 42 and the fuel/air mixture is introduced into combustor 16from an outlet 48 of swirler assembly 42.

FIG. 3 is a perspective view of a dome plate 52 that forms a part ofdome assembly 40. Dome plate 52 is an annular member having asubstantially circular profile. Dome plate 52 includes a plurality ofopenings or eyelets 54 circumferentially spaced between an inner radiusR₁ and an outer radius R₂ of dome plate 52. Dome plate 52 has a forwardor upstream facing side 56 and an aft or downstream facing side 58. Abushing or seal plate 60 is mounted on dome plate 52 at each eyelet 54.Dome plate 52 also includes an inner circumferential flange 62 and anouter circumferential flange 64 that are used to couple dome assembly 40to combustor 16. In the exemplary embodiment, dome plate 52 is formed bya stamping operation and seal plate 60 is brazed to dome plate 52. Thebraze is applied to aft side 58 of dome plate 52 and flows to forwardside 56. The braze joint can be visually inspected from forward side 56to confirm that the braze joint is complete. Brazing provides structuralstrength between dome plate 52 and seal plate 60.

FIG. 4 is an enlarged cross-sectional view of dome assembly 40 shown inFIG. 2. Dome assembly 40 includes dome plate 52 with seal plate 60,swirler assembly 42, and a baffle 68. Dome plate 52, seal plate 60, andbaffle 68 are aligned coaxially with an axial centerline 70 of swirlerassembly 42. Swirler assembly 42 includes a primary swirler 74 and asecondary swirler 76.

Primary swirler 74 includes a body 78 that is generally cylindrical inshape and includes fuel inlet 46 at a forward end 80. Fuel inlet 46opens into a fuel inlet channel 82 in body 78. Body 78 includes a base84 and a generally circular flange 86 that extends radially outward frombase 84. Flange 86 abuts secondary swirler 76. A plurality ofpassageways 88 are formed in base 84. Passageways 88 admit air intoprimary swirler 74 that mixes with fuel and imparts a swirling action tothe fuel/air mixture.

Secondary swirler 76 includes a venturi section 90 from which asubstantially circular flange 92 radially extends. A retainer ring (notshown) coupled to secondary swirler 76 holds primary swirler 74 insliding engagement with secondary swirler 76. Some movement is allowedbetween primary swirler 74 and secondary swirler 76 to facilitateinstallation of a fuel injector on primary swirler 74. A flare conesection 96 is formed integrally with secondary swirler 76. Flare conesection 96 includes an exit cone 98, a substantially circular midsection 100, and a substantially circular flange 102. A plurality ofswirler vanes 104 extend between flange 92 and flange 102. Flanges 92and 102 define a swirler vane channel 106 that circumscribes venturi 90.Swirler vanes 104 are circumferentially spaced around venturi section 90and are oriented so as to impart a swirling motion to air flowingthrough swirler vane channel 106. Flare cone section 96 includes acooling air circuit that directs cooling air against an underside 110 ofexit cone 98.

Venturi section 90 includes an outer wall 112 and an inner wall 114 thatdefines an axial flow path 116 that extends through venturi section 90along axial centerline 70 of swirler assembly 42. Venturi section 90includes a throat 118 and a venturi exit 120. Throat 118 has aconverging-diverging cross sectional profile that extends from a forwardfacing surface 122 of flange 92 flange to venturi exit 120. Venturithroat 118 has a minimum diameter D₁. Venturi exit 120 extends into athroat 130 of flare cone section 96. Venturi exit 120 has a an outerdiameter D₂ that is less than an inner diameter D₃ of throat 130 offlare cone section 96 such that a space 132 circumscribes venturi exit120. Space 132 is in flow communication with swirler vane channel 106.

Exit cone 98 of flare cone 96 includes an inner wall 134 that defines aflare cone flow path 136 that extends along axial centerline 70 ofswirler assembly 42. Flow path 136 culminates at swirler exit 48. Exitcone 98 is exposed to a combustion zone (not shown) within combustor 16.Flare cone section 96 is provided with a cooling circuit to cool exitcone 98. Flange 102 includes air holes 140 circumferentially spacedaround a perimeter 142 of flange 102. Internal channels 144 cast intoflange 102 and mid section 100 route cooling air to delivery holes 146that direct cooling air to underside 110 of exit cone 98 to cool exitcone 98 and baffle 68. In an alternative embodiment, internal channels144 are machined into flange 102 and mid section 100.

Baffle 68 is generally cylindrical in shape and includes a heatdeflecting portion 150 that extends radially outward from an axialportion 152 that is coupled to seal plate 60. In the exemplaryembodiment, baffle 68 is welded to seal plate 60. The welded attachmentof baffle 68 to seal plate 60 facilitates repair and replacement ofbaffle 68.

Dome assembly 40 is fabricated by first stamping a dome plate 52 thatincludes a plurality of substantially circular openings or eyelets 54. Aseal plate 60 is then brazed to dome plate 52 at each eyelet 54. In thebraze operation, braze is applied to an aft side 58 of dome plate 52.Inspection of the braze joint is achieved visually by confirming thepresence of braze filler from the forward side 56 of dome plate 52 afterthe braze heat cycle. In the exemplary embodiment, the sealplate-to-dome plate joint is the only brazed joint in dome assembly 40,which facilitates service and repair and also reduces rework. After sealplate 60 is installed, a baffle 68 is coupled to seal plate 60. In theexemplary embodiment, baffle 68 is welded to seal plate 60. Seal plate60 and baffle 68 are assembled such openings in seal plate 60 and baffle68 are concentric with eyelets 54 in dome plate 52.

Dome assembly 40 is completed by coupling a swirler assembly 42 havingan integrally formed flare cone assembly 96 to each seal plate 60. Incoupling swirler assembly 42 to seal plate 60, exit cone 98 of flaircone assembly 96 is passed through openings in eyelet 54, seal plate 60,and baffle 68. In the exemplary embodiment, swirler assembly 42 iswelded to seal plate 60.

During operation, fuel is delivered to inlet 46 of primary swirler 74.The fuel is mixed with air and the fuel/air mixture is channeleddownstream through venturi section 90 of secondary swirler 76. Fuel/airmixture exits venturi section 90 and is mixed with swirling air fromswirler vane channel 106. Flare cone section 96 receives swirled airfrom swirler vane channel 106 and a fuel/air mix from venturi section 90that is discharged into throat 130 of flare cone section 96. Thefuel/air mixture is spread radially outward as it exits swirler assembly42 through exit cone 98 and enters a burning zone within combustor 16.Cooling air is channeled through flange 102 and delivered between baffle68 and underside 110 of exit cone 98. More specifically, cooling air isrouted through channels 144 in flange 102 and directed towards underside110 of exit cone 98.

The above-described dome assembly for a gas turbine engine combustor iscost-effective and reliable. The dome assembly is fabricated with onlyone braze joint which facilitates service and repair and reduces reworkduring initial assembly. The integrity of the braze joint can bevisually inspected after a braze oven heat cycle. The dome assemblyincludes a swirler assembly that has an integral flare cone thatincludes a cooling circuit to cool the flare cone and baffle. As aresult, the fabrication costs of the dome assembly are reduced whileserviceability and reliability are improved.

Exemplary embodiments of combustor dome assemblies are described abovein detail. The assemblies are not limited to the specific embodimentsdescribed herein, but rather, components of each assembly may beutilized independently and separately from other components describedherein. Each dome assembly component can also be used in combinationwith other dome assembly components.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

1. A method for fabricating a dome assembly for a gas turbine enginecombustor, said method comprising: forming an annular dome plateincluding a plurality of substantially circular eyeletscircumferentially spaced thereon; coupling a seal plate to the domeplate at each eyelet such that an opening defined in each seal plate isaligned substantially concentrically with respect to a respectiveeyelet; coupling a baffle to each seal plate such that an openingdefined in each baffle is aligned substantially concentrically withrespect to a respective eyelet; and coupling a swirler assembly havingan integrally formed swirler and flare cone to each seal plate such thatthe flare cone extends at least partially through the baffle opening,and such that cooling air may be directed towards the flare cone throughopenings formed in the assembly.
 2. A method in accordance with claim 1wherein forming an annular dome plate comprises forming the dome platethrough a stamping process.
 3. A method in accordance with claim 1wherein coupling a seal plate to the dome plate comprises brazing theseal plate to the dome plate, such that braze is applied to an aft sideof the seal plate.
 4. A method in accordance with claim 1 whereincoupling a swirler to the seal plate comprises welding the swirler tothe seal plate.
 5. A dome assembly for a gas turbine engine combustor,said dome assembly comprising at least one swirler assembly comprising aprimary swirler and a secondary swirler, said secondary swirler formedintegrally with a flare cone, said secondary swirler comprising acooling circuit formed therein channeling cooling air towards said flarecone.
 6. A dome assembly in accordance with claim 5 wherein said flarecone comprises a flange, said cooling circuit comprises a plurality ofchannels formed in said flange, each of said channels for channelingcooling air towards said flare cone for impingement cooling of saidflare cone.
 7. A dome assembly in accordance with claim 5 furthercomprising an annular dome plate and a seal plate each coupled to saiddome plate, said seal plate comprising an opening extendingtherethrough, said dome plate comprising an opening extendingtherethrough, said dome plate opening is aligned substantiallyconcentrically with said seal plate opening.
 8. A dome assembly inaccordance with claim 7 wherein said seal plate is brazed to said domeplate.
 9. A dome assembly in accordance with claim 7 wherein said domeplate opening and seal plate opening are each sized to receive saidflare cone therethrough.
 10. A dome assembly in accordance with claim 7further comprising a baffle coupled to said seal plate.
 11. A domeassembly in accordance with claim 10 wherein said cooling circuit isconfigured to channel cooling air between said flare cone and saidbaffle.
 12. A dome assembly in accordance with claim 10 wherein saidbaffle comprises an opening extending therethrough, said baffle openingis aligned substantially concentrically with respect to said dome plateopening.
 13. A gas turbine engine comprising a combustor comprising atleast one dome assembly comprising at least one swirler assembly,comprising a primary swirler and a secondary swirler, said secondaryswirler formed integrally with a flare cone, said secondary swirlercomprising a cooling circuit defined therein for channeling cooling airtowards said flare cone.
 14. A gas turbine engine in accordance withclaim 13 wherein said flare cone comprises a flange, said coolingcircuit comprises a plurality of channels formed in said flange forchanneling cooling air to said flare cone for impingement cooling ofsaid flare cone.
 15. A gas turbine engine in accordance with claim 13further comprising an annular dome plate and a seal plate coupled tosaid dome plate, said seal plate comprising an opening extendingtherethrough and aligned substantially concentrically with an openingextending through said dome plate.
 16. A gas turbine engine inaccordance with claim 15 wherein said seal plate is brazed to said domeplate.
 17. A gas turbine engine in accordance with claim 15 wherein saiddome plate opening and said seal plate opening are each sized to receivesaid flare cone therethrough.
 18. A gas turbine engine in accordancewith claim 15 further comprising a baffle coupled to said seal plate.19. A gas turbine engine in accordance with claim 18 wherein saidcooling circuit is configured to channel cooling air between said flarecone and said baffle.
 20. A gas turbine engine in accordance with claim13 wherein said at least one air swirler further comprises a venturiextending between said primary and said secondary swirlers.